High voltage power transmission lines carrying voltages in the hundreds of kilowatt range have been constructed to extend from spaced towers, poles or other vertical supports (hereinafter collectively referred to as “towers”) in terrain which is often practically inaccessible to land vehicles. In recent years, a number of methods and devices have been developed to facilitate the repair and maintenance of high voltage power transmission lines which are accessed by helicopter.
Towers having davit arms are frequently employed for supporting multiple high voltage electrical conductors. The conductors are typically supported under the arms of such towers using a suspension insulator for each conductor. Periodically, it is necessary to replace the insulators because they are visibly damaged, as part of a general maintenance plan or for some other reason. Typically, an insulator is attached via a pin to each davit arm and via a pin to a shoe which supports the conductor. These pins, typically, must be manually removed by linemen placed on the tower via helicopter in order to replace the insulators. Pin removal typically requires either bare-handed contact with energized components or shut down of electrical flow in the conductor. Damaged or worn insulators are typically removed from the tower via helicopter and replacement insulators are delivered to the tower via helicopter. However, when the davit arms are narrow and lightweight, they cannot safely support a lineman and the equipment necessary for removing and replacing insulators. Therefore, the conventional manner of removing and replacing insulators, where the lineman and his equipment are supported on and work from the tower arm, cannot be used. This presents a particular problem for safely accessing and replacing the insulators on each davit arm.
Accordingly, there exists a need for a method and apparatus for safely accessing the insulator, energized conductor and their hardware, disconnecting the energized conductor from the insulator, disconnecting the insulator to be replaced from the davit arm and obtaining and connecting a replacement insulator, all without utilizing the davit arm to support the lineman and without exposing the lineman to the risk of contacting the grounded tower while handling the energized conductor.